The invention relates to a rail used as an anti-rotation guide for the valve drive of an internal combustion engine having receiving spaces, which are arranged in a row at a distance from one another within the rail and accommodate inserted valve lifters that are provided as roller tappets with two parallel anti-rotation guide areas being formed on the outer surface of each roller tappet in the form of planar flattened zones, which rest on guide areas of the inventive rail provided inside the corresponding accommodating space and with the accommodating space of the inventive rail having an insertion opening in the form of a key hole, into which the respective roller tapped is inserted in the direction of its longitudinal axis, subsequently axially shifted towards the guide areas of the inventive rail serving as the anti-rotation guide and then again be displaced in the axial direction.
Such a guide rail is used in internal combustion engines in order to prevent the rotation of valve lifters embodied as roller tappets. Simultaneously it serves as an assembly aid and can be used particularly for the roller tappets of a push rod valve drive.
The publication DE 197 12 610 A1, which shows a guide rail for an internal combustion engine, explains that usually internal combustion engines are provided with roller valve lifters, which engage protrusions on camshafts. Due to the fact that the tappets must not rotate around their longitudinal axis because the rolls at the tappets are to remain at the same plane as the protrusions on the cam shaft, the tappets are aligned in a suitable manner in the cylinder block of the internal combustion engine by way of certain holding devices, preventing their rotation.
A guide rail 1, according to a prior proposal of the present applicant, shown in FIG. 5 in the attached drawing, is provided with several spaces 2, arranged in a row at a distance from one another for accepting the valve lifters 3. Two spaces 2 each are arranged as a pair and connected via an insertion bore 4, through which a valve lifter 3, which is provided with a trumpet-shaped end 5, can be inserted. The valve lifter 3 is provided with flattened zones at its exterior surface. Said flattened zones cooperate with the flattened zones 6 of the guide rail 1, which are allocated inside the spaces 2, when the valve lifter 3, inserted into the insertion bore 4, are displaced from there into one of the two spaces 2, which are arranged in pairs. During said motion, the longitudinal axis of the valve lifter 3 is shifted parallel. Now, the flattened zone of the valve lifter 3 and the flattened zones 6 of the guide rail 1 support one another so that a rotation around the longitudinal axis of the valve lifter 3, held by the guide rail 1, is not possible.
After the displacement out of the insertion bore 4 into the space 2, the valve lifter 3 is pulled downward in the direction of its longitudinal axis. Here, the trumpet-shaped end 5 of the valve lifter 3 enters recesses 7 of the guide rail 1, formed in the shape of a segment of a circle, and which are allocated to each of the spaces 2. In this manner, any movement of the valve lifter 3 back into the insertion bore 4 is prevented. When the guide rail 1 is completely equipped with valve lifters 3, it can be mounted to the internal combustion engine.